Improvement in screw-propellers



PATENT OFFICE.

MARTIN `M. WILSON, OE HONEY GnovE, TEXAS.

lmlPnovrmENTIN SCREW-PROPE'LLERS.

Specification forming part of Letters Patent No. 136,015, dated February 18, 1873.

To all whom 'it may concern.-

Be it lknown that I, MARTIN M. WILsoN, of Honey Grove, in the county of Fannin and State ofTexas,have invented anew and useful Improvement in Steam- Vessels, of which the following is a specification:

My` invention consists in means for guiding pivoted propeller-blades so that they can open and close readily and uniformly. It also consists in a new mode of applying a spring thereto so that they Obliquity or resistance of the blades will be automatically graduated.

Figure lis a side elevation of a bow and stern'quarter of a vessel with my improved blade. IFig. 2 is a horizontal section of Fig. 1, taken on the line x x.

Similar letters of reference. indicate corresponding parts.

A represents the bow quarter. B represents three vertical curved guides, suspended parallel with the ships side, at equal distance from it and from each other, by any suitable frame or guard, C, projecting from lthe ships side above the waterline so that the guides project into the water. These guides are designed to receive the swells thrown off from the bows, and so divide, separate, anddeect them along the sides of the vessel that they will be broken and destroyed, and prevented from injuriously washing the banks of .the canal. They also serve to direct the water onto the propeller to good advantage. D represents the stern quarter; E, the shaft of the propeller, arranged under the quarter. Fis the housing, outside vthe propeller, for directing the water through the passage G to the propeller; also for confining it'so as to lessen the lateral displacement, and prevent swells from being generated.` H represents a rudder pivoted to the rear side of the housing so as to form a prolongation of it, and aid in the services for which the housing is used, while performing its special function. I represents the blades of the propeller, which are pivoted near the front edge to the radial arms projecting from the shaft. At or near the rear edge they are connected by rods L to a collar, M, fitted on aprolongation 'of the propeller shaft so asto slide on it. O is a coiled spring on the shaft confined between the collar and the hub or adjusting-nut P. This spring is contracted between the collar and the nut so as to draw the blades of the propeller baolb ward and hold them on a sharp pitch when the vessel is light and the resistanceof the `water on the blades is at the minimum, and thereby prevent the rapid motion and the loss the water if the pitch were fine as needed `when the vessel is loaded.

When the vessel is loaded and the resistance on the blades is increased, and a finer pitch required the spring will further contract in proportion to the resistance, and the pitch will be changed as demanded by the amount of the load, and the slip will be proportionately lessened. At the same time, the propeller willhave the same effect upon the engine as a marine-governor to regulate its speed.

required by the adjustingnut P. The power of the blades will be transmitted mainly through the collar and the spring, particularly when the vessel is loaded, which I believe will give better results than when transmitted directly to the hub of the shaft from the blades in the ordinary way.

This arrangement of variable blades and a spring affords a gain or saving of power, and consequently of fuel7 under any circumstances, whether the boat is light or loaded. For instance, the spring is contracted between the nut at the hub and loose collar` on the rear of the shaft, so as to hold the blades of the screw against a support on the hub of propellershaft at about the same angle as the ordinary screw, whenthe propeller is at rest; but when putin motion, the spring further contracts in proportion to the resistance, and gives a less angle to the blades, or finer pitch than when at rest, even if the boat is light, and consequently overcomes the slip as well when light as when loaded, and the amount ot' force required to contract the spring further than when at rest is not lost, but actsV as a propel ling force through the spring, and gives an inclination forward while the blades are at a less angle 5 by which construction and arrangement the percentage of the slip is greatly diminished, although the blades are at a coarser pitch than when the boat is loaded and the resistance greater.

To illustrate,we will suppose that the propeller-blades are set at a pitch of forty degrees of power that would be expended in chopping The tension of the spring will be varied as I for a given load, the spring having the proper tension, so that when the power is applied and the propeller put in motion the resistance of the water on the blades will change the pitch to, say, thirty degrees. Now, we hold that the same number of revolutions will be obtained in a given time with less expenditure of power than would be required if the blades were made fast at forty degrees, While we would have about the same momentum or incliuation forward of the shaft and boat. EX- periments made indicate this result; hence our conclusions.

These variable propeller-blades are applicable to vessels of all kinds using screwpropellers, whether for canal, river, lake, or ocean navigation.

The rudders, being mounted on housings, are so placed as to be rather an advantage to the propellers than otherwise, and render the vessel more sensitive to her helm than when arms, in combination with the sliding collar M, connected thereto by rods L, as and for the purpose described.

2. The combination, with slide M connected by rods L with pivoted blades I, of the spiiial spring O, arranged upon propeller-shaft between said slide and the nut D, as and for the purpose described.

MARTIN M. WILSON.

Witnesses:

' A.' L. Woon, N. B. SMITH. 

